Add Friend not changing to Request Sent after clicking Add Friend

Question

Am using following code to send request to user (BELLOW IS JUST A PART OF FILE)

            //addFriend functionality
            if (isset($_SESSION['username']) && $_SESSION['username'] != "") {
                $isFriend = false;
                $reqSent = false;

                $frd = getUsersFriends($user);
                foreach ($frd as $f) {
                    if ($_SESSION['username'] == $f[0]) {
                        $isFriend = true;
                    }
                }

                $req = getUsersReqs($loggedIn);

                #print_r($req);

                foreach ($req as $r) {
                    if ($user == $r[0]) {
                        $reqSent = true;
                    }
                }

                if ($isFriend == false && $reqSent == false && $_SESSION['username'] != "$user") {


                    <form method="post" action="">
                        <input type="hidden" name="request" value="<?php echo $user; ?>">
                        <input type="submit" value="Add Friend"/>
                    </form>

                    <?php
                } elseif ($isFriend == false && $reqSent == true && $_SESSION['username'] != "$user") {
                    echo "Friend Request Pending";
                }
            }
            ?>

But after clicking on Add Friend it should change to Request Sent but it doesn't works

and here are function used in above code

function getUsersFriends($user) {//gets the usernames of all friends of $user
    global $db;
    $usersFriends = array();
    $stmt = $db->prepare('SELECT user2 FROM friends WHERE user1=:username');
    $stmt->execute(array(':username' => $user));
    $friends = $stmt->fetch(PDO::FETCH_ASSOC);

    if (is_array($friends) || is_object($friends)) {
        foreach ($friends as $newUser) {
            array_push($usersFriends, $newUser);
        }
    }
    #print_r($usersFriends);
    return $usersFriends;
}
function getUsersReqs($user) {//gets the usernames of all request from $user
    $usersReqs = array();
    global $db;
    $stmt = $db->prepare('SELECT user2 FROM requests WHERE user1=:username');
    $stmt->execute(array(':username' => $user));
    $requests = $stmt->fetch(PDO::FETCH_ASSOC);
    foreach ($requests as $newUser) {
        array_push($usersReqs, $newUser);
    }
    return $usersReqs;
}